Reading of magnetic tapes is now performed by read heads either of the magnetic type or of the magnetooptical type. The magnetic heads are generally suitable only for reading magnetic tapes with high advancing speed, while the heads of the magnetooptical type are suitable for low advancing speeds of these magnetic tapes.
It is known to pick up the data provided by the transducer (in general a garnet) of such a magnetooptical head by sending a light ray to this transducer and by analyzing the reflected ray with the help of a photoelectric sensor. The optical part of such a sensor system is bulky and is not suitable for multitrack heads whose zone to be read has an oblong shape.